In the recent years, health hazards (hereinafter, called food allergies) arising from food items containing an allergenic substance (hereinafter, called an allergen) have been seen here and there across the whole world. Food allergies occur when the body's immune system reacts with a particular type of substance or component contained in a food item. Since currently there is no definitive treatment method, the most assuring way of preventing food allergies is avoiding the intake of the food items containing the allergens. An allergic symptom has a possibility to even threaten one's life, and thus, the labeling of allergen-containing raw materials included in food items is imperative for an allergy patient.
Against such a background, a 1999 Session of a Joint FAO/WHO Food Standards Programme (Codex Alimentarius Commission) agreed that labeling of foods containing eight kinds of raw materials known as allergens must indicate that the food contains such substances, and the member nations are now required to consolidate the specific labeling method suitable for their respective legal systems.
In Japan, it was stipulated by the then Ministry of Health, Labor and Welfare that in view of the extent and frequency of the past health problems, etc., if 25 specific raw materials proven to induce severe allergy symptoms were included, the raw materials must be indicated (currently the Consumer Affairs Agency has the jurisdiction, and a total of 27 items including 7 items for which labeling is mandatory and 20 items for which labeling is recommended are included).
Soy sauce, which is a traditional fermented seasoning of Japan and is indispensable in Japan's dietary culture, is obtained by fermenting and brewing koji, which is prepared from soybean and wheat, and a salt solution. However, both soybean and wheat have been listed as food items containing allergens within Japan and in CODEX.
Although it is believed that the allergens are reduced in soy sauce since the raw materials are broken down by the enzymes in koji, patients allergic to soybean or wheat were not possible to use soy sauce depending on the extent of health hazards. Particularly, cereals containing gluten, such as wheat, are known to cause severe symptoms in patients with celiac disease, and the development of gluten-free food items is in demand across the world. Thus, there is a strong demand for substitute seasonings having the taste and aroma of soy sauce, without the use of any food items containing allergens (hereinafter, called allergen-free).
In response to such a demand, there have been disclosed methods that do not use soybean and wheat, such as a method of producing koji using horse bean, and then performing fermentation and maturation by adding salt water (for example, see Patent Document 1), a method of producing koji using a mixture of mustard seeds and corn, and then performing fermentation and maturation by adding salt water (for example, see Patent Document 2), a method of producing a soy sauce-like liquid seasoning with millet as the main constituent (for example, see Patent Document 3), a method of producing a fermented seasoning with Perilla ocymoides as the raw material (for example, see Patent Document 4), a method of producing fish sauce (for example, see Patent Document 5), and a method of producing soy sauce-like seasoning with tomato as the raw material (for example, see Patent Document 6). Although horse bean is not considered as a food item containing an allergen, the fact that horse bean causes favism is seen as a problem in all parts of the Mediterranean coast, North Africa, and central Asia (for example, see Patent Document 1). Moreover, since it has the distinctive flavor of horse bean even after being formed into a soy sauce-like seasoning, it may be difficult to use it as a substitute of soy sauce for certain purposes. In the method using a mixture of mustard seeds and corn, the flavor derived from mustard seeds, which are the raw material for spice, is still retained, and umami and aroma is also insufficient. As for the liquid seasoning with millet as the main constituent, and fermented liquid seasoning with Perilla ocymoides as the raw material, it is not only difficult to acquire the respective raw materials in a cheap and stable manner, but also difficult to use such items as substitute seasonings of soy sauce due to their distinctive flavor. While fish sauce does not use soybean and wheat, its flavor is significantly different from the regular soy sauce, and it is difficult to use it as a substitute seasoning. Further, some varieties of fish themselves are considered to be food items containing allergens, and therefore, they were inappropriate as allergen-free soy sauce-like seasonings.
The field pea plant (Pisum sativum L.) has been widely cultivated since past, and peas that are the seeds of the field pea plant are widely eaten around the world as roasted or boiled beans, uguisu-an (sweet green bean jam), ingredients of salads and stews, raw material of snack bars, and the like. Therefore, it is possible to acquire peas in a cheap and stable manner as raw material of food items. Peas are not indicated as specific raw materials containing the above-mentioned allergens specified within Japan and CODEX, and food items using peas as a raw material are possible to be consumed safely even by patients allergic to soybean and wheat.
As a technique of using peas as the raw material of fermented seasoning, a method of producing soy sauce in which field peas are used as the filled raw material is known (Patent Document 7). However, the purpose of the invention is lightening of the soy sauce, and not the realization of allergen-free, and therefore, it only uses field peas (peas) instead of the regular filled raw material of soybean and wheat, and does not comment on the raw material used in the production of seed koji.
Seed koji is a starter microorganism that is added to the koji-making raw material as a supply source of koji mold in the koji-making process for soy sauce, fermented soybean paste, sake, mirin (sweet sake for cooking), etc., and generally, the koji mold is cultured on the seed koji raw material, such as wheat bran and rice, and spores are produced. From the past, the seed koji have been widely used, and the technique of adding seed koji during koji-making is indispensable for the brewing industry even today.
Allergy symptoms may appear even from a minute amount of allergen, and in some circumstances, a severe allergy symptom such as anaphylactic shock may be induced, which may be life-threatening. Therefore, in order to produce allergen-free soy sauce, it is necessary to avoid the carryover of allergens that are derived not only from the main raw material, but also from the auxiliary raw materials such as the seed koji raw material used in the production of seed koji.
Wheat bran is used in the preparation of koji mold starter (seed koji) used in koji-making of general soy sauce koji. However, wheat bran is a part of the skin of wheat that is produced during the milling process for wheat flour, and includes mixtures such as the seed coat, perisperm, and embryo of wheat seeds. Therefore, from the viewpoint of carryover of allergens derived from wheat, it is not possible to use wheat bran in allergen-free soy sauce, which was a problem.
Soy sauce that does not use wheat as a raw material is provided to patients allergic to wheat. For example, brewed food items, such as soy sauce that makes use of seed koji using only raw materials derived from soybean and that does not at all contain components derived from wheat, are known (Patent Document 8). However, soybean is listed as one of the 20 allergens recommended to be labeled on the basis of the Food Sanitation Act, and of the item to be labeled according to CODEX specified by the Joint FAO/WHO Food Standards Programme (Codex Alimentarius Commission), and still it is not possible to realize the purpose of obtaining allergen-free soy sauce.